The kit is almost useless, and can't be used efficiently to get kills, even if you are good with it, as it kills you too. The level 6 kit is equal to the level 1 kit in terms of damage and efficiency, as it has no damage increase at all... the level 6 kit should be the equivalent of perhaps 6-12 tnt explosions, and you should have some chance of surviving, perhaps with a gapple.
P.S. the title didn't say it all, you should've expanded on why it should be removed.
PPS. The pyro kit is worse... it doesn't kill you, but it gets you killed. it's the cheapest kit in the game by far.